The use of magnetic door stops to catch and hold doors in a fixed position is known. They generally work by mounting a magnet to the door which engages a magnetically attractable strike plate on the wall or floor to secure the door in place. The principal problem associated with the use of magnetic door stops has been misalignment of the magnetic door stop and strike plate due to room maintenance, door sagging, design and construction defects and continued use. A number of attempts have been made to solve these problems.
U.S. Pat. No. 3,258,285 to R.K. Smith teaches a spring biased magnet slidably mounted in a non-magnetic tube. The magnet is retracted in the non-magnetic tube until it is in direct proximity of a second magnet fixed in a floor or wall. The magnetic attraction overcomes the pull of the spring withdrawing the slidably mounted magnet from the non-magnetic tube to secure the door. The disadvantage of the Smith patent is that the wall or floor magnets must be directly aligned with the slidably mounted door magnet to release holder. There is no self-adjusting mechanism to compensate for misalignment, door sag or the like.
U.S. Pat. No. 4,505,502 to Rioe Tomita teaches a device having a magnetically attractable strike plate housed in a conical shaped cylinder. The strike plate is cushioned to absorb some of the force of the door as it bumps against the stop as well as to provide some flexibility in alignment of the strike plate with the magnetic stop. The disadvantage of the Tomita stop and catch is that there is no direct load transfer between the magnet and the strike plate. The transfer of load is indirect through the strike plate housing.
U.S. Pat. No. 3,244,443 to M. E. Rodgers illustrates a stop and catch having a plastic shank with a permanent magnet housed at one end to catch a fixed mounted strike plate. Manual adjustments for door tilt are achieved by bending the resilient plastic shank. There is no feature for self-alignment of the stop.
U.S. Pat. No. 4,669,766 to L. J. Hanchett, Jr., et al attempts to solve the problem of alignment by teaching a device with an arcuately slidable electromagnet that can be adjusted to proper alignment and then locked in place. There is no feature for self-alignment and the device must be periodically readjusted to account for door sag or incidental movement during maintenance or door usage.
U.S. Pat. No. 3,025,559 to J. W. Basinger discloses a helical coiled spring with a magnet at its end to engage a strike plate. It has no provision for deflection or rotation of the magnet face. The tension load from the magnet is tranferred directly through the spring to the wall base.
U.S. Pat. No. 3,701,557 to Centofante and U.S. Pat. No. 3,300,239 to Dinkin teach magnetic door stops and holders with relatively movable holding magnets. In Centofante the relative movement is limited to a 180 degree pivot in a single plane and the device is manually adjustable for the door angle. In Dinkin the relative movement is accomplished by a helically coiled spring shaft mounted at one end to a wall and an axial mounted stud at the other end of the shaft projecting outward to hold a magnetic disk. The magnetic disk has a central bore with a diameter greater than the stud diameter. This diameter difference allows the disk to move or have "play" in all directions for door alignment. In Centofante there is relative and thus adjustment in only one plane with no means for self-alignment. In Dinkin while there is relative movement and thus self-adjustment capability in all directions, there is no means to buffer or cushion the relative movements on impact of the door and stop.
The present invention is intended to solve the problem of misalignment of door stop and strike plate as well as to accommodate the use of the door stop where doors and walls are non-parallel by providing a multi-directional self-adjusting door stop and catch.
Another object of the invention is to provide a door catch and stop that is self adjusting so that it need not be manually readjusted when the stop is bumped or knocked during use or during maintenance of the room.
Another object of the invention is to provide a direct load transfer from the magnet to the base plate of the stop.
Another object of the invention is to provide a means to adjust the position of the magnet to contact the strike plate in a manner to increase the magnetic holding power of the door catch.